1. Field of the Invention
The present invention relates to a structure in which a metal-cased plate such as a plate-like refractory material to be used for a sliding nozzle device attached to a molten metal vessel is fixed to a metal frame. The term plate used herein covers the upper and lower plates of a double plate unit or the upper and lower plates of a triple plate unit.
2. Description of Prior Art
Regarding a plate-like refractory material to be used for a sliding nozzle device, a metal-cased plate is known to be disclosed in Japanese Unexamined Patent Publication No. 48-6932. A number of proposals have so far been made as to how to fix a plate-like refractory material to a metal frame as can be seen in Japanese Unexamined Utility Model Publications Nos. 49-119422 and 52-115607 and Japanese Unexamined Patent Publication No. 60-234765.
In Japanese Unexamined Patent Publication No. 1-218761, there has been proposed a sliding plate positioning method based on the outside of a metal case being concentric with the nozzle hole of a sliding nozzle device so that the attachment of the sliding plate to a sliding metal frame is simplified. However, this proposal has the disadvantage that since the outer side of the metal case for positioning lies around the molten metal passage hole, if the outside dimensions of the metal case become large and the temperature difference between the metal case and the sliding metal frame becomes too large in cooling process, the clearance between the metal case and the sliding metal frame will tend to decrease. Further, the metal case has been known to get caught deep into the metal frame and the sliding plate sometimes becomes stuck resulting in a hindered exchanging operation of the sliding plate.